It depends on the cut of meat. A good filet mignon can just be grilled to medium, seasoned however you like, and be very tender all on its own.
Other cuts of steak, I marinate for a couple of days in a mixture of olive oil, balsamic vinegar, soy sauce and chopped fresh garlic. The acidity in the marinate also helps to tenderize the meat. Then I’m just careful not to overcook it.
Cheaper (ie tougher) cuts of meat have to be cooked slowly at a low temp or braised. At our grocery story, there’s a label on the package of meat that says how best to cook it: grilling, roasting, stewing, braising. I only tried my hand at braising for the first time last week when I bought some very inexpensive blade steaks. This is the recipe I used, with some small changes. I added mushrooms to the pan about half an hour before the steaks would be done. After cooking, I removed the steaks, covered them with foil, and thickened the liquid in the pan with cornstarch. Removed that from the heat, and stirred in about ⅓ cup sour cream. I served the steak and sauce over egg noodles, and everyone loved it. The steaks were falling apart, no knives needed.